If a range of R10CO drills is what you are after, then the C29R10CO set should be your choice. With 29 fractional sizes from 1/64? to 1/2" in 1/64? increments, the C29R10CO set is contained in a strong case to keep the drills tidy and in size order to make it easy to find the size you want. The R10CO drills are manufactured from High Speed Cobalt, perfect for drilling hard materials including tool steel, and have a bronze oxide finish to ensure clean and accurate holes by preventing workpiece material from sticking to the cutting surfaces of the tool. With a 135 degree split point for self-centering and to reduce the push force needed, there will be no more skidding over the surface of the workpiece. The heavy duty design of the R10 drills in the C29R10CO set means they come recommended to use in difficult materials and applications.